US4197484A - Electronic flash device with voltage display - Google Patents

Electronic flash device with voltage display Download PDF

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Publication number
US4197484A
US4197484A US05/897,751 US89775178A US4197484A US 4197484 A US4197484 A US 4197484A US 89775178 A US89775178 A US 89775178A US 4197484 A US4197484 A US 4197484A
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US
United States
Prior art keywords
voltage
auxiliary
capacitor
winding
auxiliary winding
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US05/897,751
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English (en)
Inventor
Kazuo Tanaka
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
West Electric Co Ltd
Original Assignee
West Electric Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by West Electric Co Ltd filed Critical West Electric Co Ltd
Application granted granted Critical
Publication of US4197484A publication Critical patent/US4197484A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/30—Circuit arrangements in which the lamp is fed by pulses, e.g. flash lamp
    • H05B41/32—Circuit arrangements in which the lamp is fed by pulses, e.g. flash lamp for single flash operation
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B15/00—Special procedures for taking photographs; Apparatus therefor
    • G03B15/02—Illuminating scene
    • G03B15/03—Combinations of cameras with lighting apparatus; Flash units
    • G03B15/05—Combinations of cameras with electronic flash apparatus; Electronic flash units

Definitions

  • the present invention relates to an electronic flash device used as an artificial light source for taking a photograph, and in particular to a display means for displaying the voltage developed across the main discharge capacitor.
  • Such a device has been disclosed in U.S. Pat. No. 4,068,150, which comprises a DC-DC converter circuit having an oscillation transformer, an oscillation transistor, an auxiliary capacitor for oscillating the oscillation transistor, and an auxiliary winding for maintaining the oscillation; and a light emitting diode actuated for display by means of the voltage generated in the auxiliary capacitor and auxiliary winding included in the DC-DC converter circuit.
  • the charging current to the main discharge capacitor is preferably large in view of reducing the charging time period and thus it is necessary to enhance the oscillation of the DC-DC converter, which oscillation is caused by the voltage generated across the auxiliary winding serving to supply the base current to the oscillation transistor for maintaining its oscillation.
  • the above-mentioned disadvantage can be avoided by increasing the number of windings of the auxiliary winding for enhancing the oscillation.
  • the number of windings of the auxiliary winding is increased to generate an increased voltage, a large reverse voltage is disadvantageously applied between the base and the emitter of the oscillation transistor during the quiescent period of the transistor, thus causing the oscillation transistor to be liable to be damaged.
  • an object of the present invention is to provide an electronic flash device wherein the oscillation transistor can be oscillated satisfactorily without any possibility of such damage and further the voltage across the charged main discharge capacitor can be displayed.
  • FIG. 1 is a circuit diagram illustrating an embodiment of an electronic flash device according to the present invention.
  • FIG. 2 is a circuit diagram illustrating another embodiment of an electronic flash device according to the present invention.
  • FIG. 1 shows an embodiment of an electronic flash device according to the present invention.
  • numeral 1 is a DC source
  • numeral 2 is an oscillation transistor
  • numeral 3 is an oscillation transformer including a primary winding 3a, a secondary winding 3b, a first auxiliary winding 3c, and a second auxiliary winding 3d magnetically coupled with the auxiliary winding 3c
  • numeral 4 is an auxiliary capacitor
  • numeral 5 is a diode
  • numeral 6 is a main discharge capacitor serving to supply the light emission energy to a flash discharge tube
  • numeral 8 is a switch
  • numeral 13 is a display circuit including a diode 9, resistors 10 and 11 and a light emitting diode.
  • the flash discharge tube 7 is supplied at its trigger electrode 7a with a high voltage pulse generated in a conventional trigger circuit (not shown).
  • the oscillation transistor 2 is oscillated to generate a high voltage at the secondary winding 3b of the oscillation transformer 3, and thus the main discharge capacitor 6 begins to be charged through the diode and also the auxiliary capacitor 4 is charged, in the polarity as shown in FIG. 1, as a result of the main discharge capacitor 6 being charged.
  • the voltage generated across the second auxiliary winding 3d increases in proportion to the voltage across the charged main discharge capacitor 6.
  • the voltage E 3 generated across the second auxiliary winding 3d is superposed on the voltage across the auxiliary capacitor 4 charged with the voltage generated across the auxiliary winding 3c and the superposed or resultant voltage is applied to the display circuit 13 including the diode 12. Further, the value of the superposed voltage is proportional to that of the voltage across the charged main discharge capacitor 6.
  • the display circuit 13 can, as shown in FIG. 1, properly divide the voltage applied thereto by suitably adjusting the resistance values of the resistors 10 and 11 so as to control the lighting time of the light emitting diode 12 (the starting time of the light emission) connected in parallel with the resistor 11.
  • the control of the lighting time of the light emitting diode 12 through the voltage division ratio between the resistors 10 and 11 is related to the voltage across the charged main discharge capacitor 6 and thus the voltage of the charged main discharge capacitor 6 can be displayed by setting the voltage division ratio through the resistors 10 and 11 in such a manner that the light emitting diode 12 is lit when the voltage across the charged main discharge capacitor 6 reaches a predetermined value.
  • the light emitting diode 12 is applied with the above-described superposed voltage divided through the resistors 10 and 11; then, the current flowing through the light emitting diode 12 by the divided voltage is controlled to be small. Thus the emission light of the light emitting diode 12 is too low to be perceived.
  • FIG. 2 is an electric circuit diagram of another embodiment of an electronic flash device according to the present invention.
  • the parts having the same reference numerals as those in FIG. 1 have the same functions as in FIG. 1, and a display circuit 15 is similar to the display circuit 13 except that the resistor 11 in FIG. 1 is replaced by a variable resistor 14.
  • variable resistor 14 By using the variable resistor 14, the error in the display of the voltage across the charged main discharge capacitor 6 can be avoided, such an error may be caused, for example, by the dispersion or non-uniformity in the values of the lighting voltage, that is, the voltage for providing a sufficient brightness, which is due to the characteristics of the light emitting diode.
  • the resistance value of the variable resistor 14 that is, by making variable the voltage division ratio between the variable resistor 14 and the resistor 10
  • the voltage across the charged main discharge capacitor 6 can be displayed more precisely.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Stroboscope Apparatuses (AREA)
  • Discharge-Lamp Control Circuits And Pulse- Feed Circuits (AREA)
  • Audible And Visible Signals (AREA)
  • Illuminated Signs And Luminous Advertising (AREA)
  • Dc-Dc Converters (AREA)
US05/897,751 1977-04-19 1978-04-17 Electronic flash device with voltage display Expired - Lifetime US4197484A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP52-49878[U] 1977-04-19
JP1977049878U JPS6025051Y2 (ja) 1977-04-19 1977-04-19 電子閃光装置

Publications (1)

Publication Number Publication Date
US4197484A true US4197484A (en) 1980-04-08

Family

ID=12843294

Family Applications (1)

Application Number Title Priority Date Filing Date
US05/897,751 Expired - Lifetime US4197484A (en) 1977-04-19 1978-04-17 Electronic flash device with voltage display

Country Status (4)

Country Link
US (1) US4197484A (cg-RX-API-DMAC7.html)
JP (1) JPS6025051Y2 (cg-RX-API-DMAC7.html)
DE (1) DE2816794C3 (cg-RX-API-DMAC7.html)
GB (1) GB1568796A (cg-RX-API-DMAC7.html)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4396870A (en) * 1980-07-01 1983-08-02 West Electric Co., Ltd. Electronic flash device
US4431291A (en) * 1980-06-03 1984-02-14 Nippon Kogaku K.K. Indicating device for a camera
US4496939A (en) * 1982-06-04 1985-01-29 Eastman Kodak Company Power indicator apparatus for a DC to DC flyback converter
US5051733A (en) * 1990-05-23 1991-09-24 Service Machine Company High voltage indicator device
US5065142A (en) * 1990-05-23 1991-11-12 Service Machine Company Voltage pickup circuit and flashing display for high voltage indicator device, and input electrode therefor
US6044227A (en) * 1994-10-17 2000-03-28 Fuji Photo Film Co., Ltd. Lens-fitted photo film unit and electronic flash device for use therewith

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3831079A (en) * 1971-06-14 1974-08-20 West Electric Co Electronic photographic flash apparatus
US4068150A (en) * 1975-03-14 1978-01-10 West Electric Co., Ltd. Voltage indication means for an electronic flashing device

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3831079A (en) * 1971-06-14 1974-08-20 West Electric Co Electronic photographic flash apparatus
US4068150A (en) * 1975-03-14 1978-01-10 West Electric Co., Ltd. Voltage indication means for an electronic flashing device

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4431291A (en) * 1980-06-03 1984-02-14 Nippon Kogaku K.K. Indicating device for a camera
US4396870A (en) * 1980-07-01 1983-08-02 West Electric Co., Ltd. Electronic flash device
US4496939A (en) * 1982-06-04 1985-01-29 Eastman Kodak Company Power indicator apparatus for a DC to DC flyback converter
US5051733A (en) * 1990-05-23 1991-09-24 Service Machine Company High voltage indicator device
US5065142A (en) * 1990-05-23 1991-11-12 Service Machine Company Voltage pickup circuit and flashing display for high voltage indicator device, and input electrode therefor
US6044227A (en) * 1994-10-17 2000-03-28 Fuji Photo Film Co., Ltd. Lens-fitted photo film unit and electronic flash device for use therewith

Also Published As

Publication number Publication date
DE2816794B2 (de) 1980-04-30
DE2816794C3 (de) 1981-02-05
JPS6025051Y2 (ja) 1985-07-27
DE2816794A1 (de) 1978-10-26
JPS53144342U (cg-RX-API-DMAC7.html) 1978-11-14
GB1568796A (en) 1980-06-04

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